docs: def request_sign_out(self, session=requests):
          """
          Send a POST request to the ``ServiceTicket``s logout URL to
          request sign-out.
          """
          if logout_allowed(self.service):
              request = SingleSignOutRequest(context={'ticket': self})
              url = get_logout_url(self.service) or self.service
              session.post(url, data={'logoutRequest': request.render_content()})
              logger.info("Single sign-out request sent to %s" % url)